Competitive Coordination of Ternary Anions Enabling Fast Li‐Ion Desolvation for Low‐Temperature Lithium Metal Batteries

Abstract

AbstractLithium metal batteries (LMBs) working at subzero temperatures are plagued by severe restrictions from the increased energy barrier of Li‐ion migration and desolvation. Herein, a competitive coordination strategy based on the ternary‐anion (TA) coupling of PF6−, TFSI−, and NO3− toward Li+ to achieve an anti‐freezing electrolyte with rapid kinetics is proposed. Computational and spectroscopic analyses reveal that the repulsive interaction among three anions and the preponderant coordination of the Li+‐NO3− further weaken the involvement degree of other anions in the Li+ solvation structure. As a result, the formulated TA electrolyte exhibits low binding energy of Li+‐anions (−4.62 eV), Li+ desolvation energy (17.04 kJ mol−1), and high ionic conductivity (3.39 mS cm−1 at −60 °C), simultaneously promoting anion‐derived solid electrolyte interphase on Li anode. Assembled Li||LiNi0.8Co0.1Mn0.1O2 cells employing the TA electrolyte exhibit robust capacity retention of 86.74% over 200 cycles at 25 °C and deliver a specific cathode capacity of 103.85 mAh g−1 at −60 °C. This study will enlighten the rational design of multi‐anion electrolytes to tailor the Li+ solvation/desolvation for advanced low‐temperature LMBs.